PHP把全角数字转为半角数字

//把全角数字转为半角数字 
<? 
function GetAlabNum($fnum){ 
$nums = array("０","１","２","３","４","５","６","７","８","９");
//OSPHP.com.CN
$fnums = "0123456789"; 
        for($i=0;$i<=9;$i++) $fnum = str_replace($nums[$i],$fnums[$i],$fnum); //OsPHP.COM.CN 
$fnum = ereg_replace("[^0-9.]|^0{1,}","",$fnum); 
        if($fnum=="") $fnum=0; 
        return $fnum; 
} 
?>